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Previous Issue: 31 May 2000 Next Planned Update: 1 July 2010 Page 1 of 14 Primary contact: Mohammad A. Ghamdi on 874-7954

Materials System Specification

14-SAMSS-533 29 June 2005

Three-Phase Dry-Type Power Transformers

Electrical Substations Equipment Standards Committee Members Ghamdi, Mohammed A., Chairman Carlson, Ron W., Vice Chairman Fayez, Hamad A. Gopal, Uarutharaja Hartman, Ralph A. Helfrich, Cory H. Lowe, John L. Maghrabi, Ibrahim M. Nazzawi, Abdullah O. Ojan, Jawad A. Ramadhan, Mohammed J. Refaee, Jubran A. Rewatkar, Jayesh K. Stansbury, M.C. "Chip" (ABQ PLANTS)

Saudi Aramco DeskTop Standards Table of Contents 1 Scope............................................................. 2 2 Conflicts and Deviations................................. 2 3 References..................................................... 2 4 Qualifications.................................................. 4 5 Service Conditions......................................... 4 6 Information Required with Quotation............. 5 7 General Requirements................................... 5 8 Construction................................................... 5 9 Inspection and Testing................................. 11 Data Schedule.................................................... 13

Document Responsibility: Electrical Substations Equipment 14-SAMSS-533 Issue Date: 29 June 2005 Next Planned Update: 1 July 2010 Three-Phase Dry-Type Power Transformers

Page 2 of 14

1 Scope

1.1 This specification defines the mandatory requirements for three-phase, dry-type, power transformers rated 501 kVA and larger with a high-voltage winding of 601 V or higher for operation in 60 Hz power systems.

1.2 The specific requirements of dry-type transformers shall be given in the Buyer's Purchase Order documents for this equipment.

1.3 The transformer unit shall be designed, built and tested in accordance with American National Standards Institute/Institute of Electrical and Electronics Engineers (ANSI/IEEE) Standards C57.12.01 as supplemented by this specification and all applicable companion guides and codes as referenced in ANSI/IEEE C57.12.01.

1.4 This specification defines the basic features of the equipment required and shall take precedence over all standards and codes as referenced. The equipment manufacturer shall ensure that the applicable standards are adhered to in addition to this specification.

2 Conflicts and Deviations

2.1 If there are any conflicts between this Specification and associated purchasing, project or engineering documents, this specification shall take precedence.

2.2 Direct all requests to deviate from this Specification in writing to the Company or Buyer Representative, who shall follow internal company waiver procedure.

2.3 The designation "Commentary" is used to label a sub-paragraph that contains comments that are explanatory or advisory. These comments are not mandatory, except to the extent that they explain mandatory requirements contained in this SAMSS.

3 References

The following is a summary of all the documents which have been mentioned within this Specification. The specific part(s) of these documents which are applicable have been identified throughout this Specification.

3.1 Saudi Aramco References

Saudi Aramco Inspection Requirements

Form 175-140300 Three-Phase Dry-Type Power Transformers


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Saudi Aramco Forms and Data Sheets

Form NMR-7906 Non-Material Requirements for Transformers: Small, Medium, & Large, Power & Distribution

3.2 Industry Codes and Standards

American Society for Testing and Materials

ASTM D1535 Standard Method for Specifying Color by the Munsell System

American National Standards Institute

ANSI/IEEE C57.12.01 Standard General Requirements for Dry-Type Distribution and Power Transformers Including Those with Solid Cast and/or Resin-Encapsulated Windings

ANSI/IEEE C57.12.28 Pad-Mounted Equipment-Enclosure Integrity

ANSI/IEEE C57.12.51 Requirements for Ventilated Dry-Type Power Transformers, 501 kVA and Larger, Three-Phase, with High-Voltage 601 to 34500 Volts, Low-Voltage 208Y/120 to 4160 Volts

ANSI/IEEE C57.12.52 Requirements for Sealed Dry-Type Power Transformers, 501 kVA and Larger, Three-Phase, with High-Voltage 601 to 34500 Volts, Low-Voltage 208Y/120 to 4160 Volts

ANSI/IEEE C57.12.91 IEEE Standard Test Code for Dry-Type Distribution and Power Transformers

International Electrotechnical Commission

IEC 60227 Polyvinyl Chloride Insulated Cables of Rated Voltages up to 450/750 Volts

IEC 60227-1 Part 1: General Requirements

IEC 60227-2 Part 2: Test Methods

IEC 60227-3 Part 3: Non-sheathed Cables for Fixed Wiring

IEC 60332 Tests on Electric Cables Under Fire Conditions

IEC 60332-1 Part 1: Test on a Single Vertical Insulated Wire or Cable

IEC 60332-3 Part 3: Test on Bundled Wire or Cables


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IEC 60502 Power Cables with Extruded Insulation and their Accessories for Rated Voltages from 1 kV up to 30 kV

IEC 60502-1 Part 1: Cables for Rated Voltages of 1 kV and 3 kV

National Electrical Manufacturers Association

NEMA ICS 6 Enclosures for Industrial Control and Systems

NEMA TR 1 Transformers, Regulators and Reactors

National Fire Protection Association

NFPA 70 National Electrical Code (NEC)

4 Qualifications

Transformer designs and materials used in the transformer shall have a minimum of two (2) years of verifiable, satisfactory performance and proven field experience.

5 Service Conditions

5.1 As specified in the DATA SCHEDULE Ventilated Self-cooled Class AA or Ventilated self cooled / forced-air-cooled Class AA/FA transformers shall be utilized indoor. Only sealed self-cooled, Class GA transformers shall be used outdoor. Unless otherwise specified they shall be suitable for continuous operation at locations up to an altitude of 1000 meters.

5.2 Outdoor equipment supplied under this specification shall be suitable for use in locations that are subject to sand and dust storms, fog, and air borne contaminants, including NaCl (Sodium Chloride) to 300 ppm and MgCl (Magnesium Chloride) to 50 ppm.

5.3 Unless otherwise specified, equipment shall be suitable for use in locations with the following ambient temperatures:

a) Average monthly normal maximum (hottest month), 45°C;

b) Average daily temperature (hottest month) 40°C;

c) Maximum daily peak 50°C.

6 Information Required with Quotation

6.1 The Vendor shall supply the following information with the Quotation. This is in addition to the information required within the Quotation Request or Purchase


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Order Documents.

6.1.1 Fully completed DATA SCHEDULE.

6.1.2 Certified Design Tests Certificates for the tests performed as outlined in ANSI/IEEE C57.12.01 as necessary for the equipment to be purchased as specified in the DATA SCHEDULE.

6.1.3 User's List of the same equipment which has been in service for a minimum of two (2) years. The list should indicate as a minimum:

a) User company name and address

b) Installation site and contact address

c) Date of installation

6.2 The "Certified Design Tests" Certificates mentioned above shall be from, or endorsed by an independent testing laboratory and shall provide clear, traceable evidence that the subject tests were performed.

7 General Requirements

7.1 This specification shall take precedence over any referenced third party document(s). Technical reference documents shall be of the latest issue.

7.2 The Voltage ratings, Kilovolt-Ampere ratings and Basic Lightning Impulse Levels (BILs) for ventilated dry-type Power transformers shall be in accordance with ANSI/IEEE C57.12.51 as applicable and for sealed dry-type shall be in accordance with ANSI/IEEE C57.12.52.

7.3 All documentation shall be in the English language.

7.4 Saudi Aramco form NMR-7906 provides information on non-material requirements.

8 Construction

8.1 Enclosure (Housing)

8.1.1 Transformer enclosure shall conform to the requirements of ANSI/IEEE C57.12.28, "Pad-mounted Equipment Enclosure Integrity", except the paint shall be light gray number 61 in accordance with ASTM D1535 (Munsell Notation 8.3 G6 10/0.54), unless otherwise specified.

8.1.2 Transformer enclosure shall be self supporting, non-combustible, moisture resistant and protected against corrosion. Enclosure design


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shall be such as to permit easy access to the high and low voltage terminals for outgoing cable connections. Access to the core and coil assembly for inspection and testing shall also be provided.

8.1.3 Transformer enclosures for indoor use shall be ventilated drip-proof, NEMA ICS 6 Type 2, unless otherwise specified. All ventilation openings shall be protected against falling dirt.

8.1.4 All transformers shall bear permanently attached nameplates.

8.1.4.1 The nameplates shall be stainless steel and attached with stainless steel hardware. Entries shall be marked by etching, engraving or other permanent marking method.

8.1.4.2 The nameplate shall be in the English language according to American usage.

8.1.4.3 Danger and warning labels shall be written in both Arabic and English, utilizing white characters on a red background. If noted in the Purchase Order the Arabic warning labels will be provided by others.

8.1.5 In addition to the transformer data the nameplate(s) shall also include the following which may be on a separate plate:

1) Manufacturer's plant location

2) Buyer's Purchase Order number

3) Manufacturer's Order reference number

4) Equipment year of manufacture

5) Equipment Serial Number

6) Equipment Model Number

8.2 Cores

8.2.1 Cores shall be fabricated using high grade, grain-oriented silicon steel laminations with high magnetic permeability. Maximum magnetic flux densities shall be kept well below the saturation point. The core laminations shall be tightly clamped and compressed. All cuts to be burr-free and to exact length. Core clamps and all structural parts shall be grounded to prevent induced voltage build up.

8.2.2 Cores shall have flush bottoms. Design and fabrication shall be done in such a manner that will minimize losses and audible sound level.


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8.3 Coils

8.3.1 The high and low voltage coils shall be constructed of electrical grade copper as an assembly and shall be able to withstand the mechanical and thermal stresses produced by external short circuits under the conditions specified in ANSI/IEEE C57.12.01.

8.3.2 Coil construction shall be designed to limit transformer winding temperature rise when operating at nominal kVA rating to:

• 80°C Average winding temperature rise (by resistance)

• 110°C Hot spot winding rise.

8.3.3 Transformer core and coil assemblies shall be completely emersed in an insulating resin or varnish and oven cured, or encapsulated with polyester (epoxy) resin using a Vacuum Pressure Impregnation (VPI) process. Cores for transformers utilizing solid cast coil winding (coils in an epoxy mold completely sealed) shall be completely emersed in an insulating resin or varnish and oven cured. As specified in the DATA SCHEDULE the transformer coils shall be resin encapsulated construction or solid cast (coils in a mold completely sealed) construction.

8.4 Taps

Each Transformer shall be furnished with facilities for changing taps with the transformer de-energized. Tapping shall be on the high voltage winding to allow for variation of the incoming primary voltage. Unless otherwise specified, transformers shall have two voltage taps 2-½% below normal voltage and two voltage taps 2-½ above normal voltage. All taps shall have full current capacity.

8.4.1 Ventilated Dry-Type transformers shall be provided with facilities for changing taps that provide easy access to the tap terminals. The tap terminals shall be grouped so that the taps are changed by moving terminal strips (jumpers) from one connection point to another. The tap connections shall be clearly marked.

8.4.2 Sealed Dry-Type transformers shall be provided with a tap changer for de-energized operation. The operating handle shall be brought out through the enclosure at a convenient height for the design. The tap connection shall be clearly marked. The tap changer handle shall have provision for padlocking and shall provide visible indication of the tap position without unlocking.


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8.5 Winding Connections

Unless otherwise specified, all transformers shall have delta-connected high voltage windings and wye-connected low voltage windings. The angular displacement between high-voltage and low-voltage phase voltages shall be 30 deg, with the low voltage lagging the high voltage.

8.6 Insulation

8.6.1 The insulation system shall be a minimum of ANSI Class 185 Insulation.

8.6.2 All insulation materials shall be flame retardant and shall not support combustion.

8.6.3 All materials shall be resistant to ozone, or otherwise protected from ionization products.

8.7 Impedance

The guaranteed values of impedance at self cooled rating shall be referenced to the rated voltage tap and shall be not less than 4% at 80°C (subject to tolerance specified in ANSI/IEEE C57.12.01).

8.8 Cooling

Transformers shall be self-cooled Ventilated Class AA or Sealed Class GA. Forced-air cooling may be specified for Ventilated self cooled/forced-air-cooled Class AA/FA transformers.

8.8.1 The forced air cooling system shall include:

a) thermal sensors, b) fans, c) control wiring, d) control box with test switch, e) current limiting fuses, f) indicating lights, g) alarm, h) alarm silencing relay, and i) push buttons.

8.8.2 The cooling fans and controls shall be capable to operate on 120 V AC, single phase, unless other auxiliary voltage is specified in the DATA SCHEDULE.


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8.8.3 All fans shall be fitted with protective fan guards or located within the transformer enclosure to protect personnel from incidental access. The fan guards shall have wires spaced to limit openings to less than 12.7 mm.

8.9 Base

8.9.1 All transformers shall be equipped with the permanent heavy duty base assemblies suitable for skidding in any direction.

8.9.2 The transformer base shall have provisions for lifting and/or jacking the unit. This feature shall be appropriately described on preliminary and final drawings.

8.9.3 Anti vibration mountings are required for floor mounted transformers located indoors. Anti vibration pads shall be fitted between the enclosure and its mounting. Electrical continuity, for grounding, shall be maintained between these components.

8.10 Control and Terminal Enclosures

8.10.1 When required, terminal enclosures shall be NEMA ICS 6 Type 3. Undrilled gland plates are not acceptable. For transport prior to erection, conduit hubs shall be fitted with threaded steel plugs; bus duct and pothead entrances shall be fitted with steel plates.

8.10.2 When required, control cabinets and accessory wiring shall be separate from terminal enclosures and shall incorporate the following:

1) Control cabinet(s) shall be mounted on the transformer, or within the transformer enclosure shall be accessible from grade, and shall house all terminal connections for transformer accessories, control equipment and other devices. All wiring requiring external connections shall be terminated to terminal blocks. Terminal blocks shall be one piece, phenolic barrier type, rated 20 A, 600 V minimum with prenumbered marking strips and suitable for two terminations per point. Shorting terminal blocks shall be provided for current transformer circuits and shall be capable of receiving 10 mm² (8 AWG) wire.

2) Outdoor control cabinet(s) shall be NEMA ICS 6 Type 3 suitable for bottom entry. Cable or conduit top entry is not acceptable. Doors shall be hinged, capable of opening not less than 120°, and equipped with stainless steel hardware including locking devices.

3) Outdoor Control cabinet(s) shall be provided with a space heater, suitable for 120 V AC operation but rated for 240 V. A


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disconnecting means shall be provided for each power supply. A wiring diagram, printed on weather resistant material indicating the control cabinet circuits and fuse or circuit breaker ratings shall be affixed inside the cabinet door.

4) All relays, switches, and terminal blocks shall be securely attached with screws.

5) Wiring shall be run in hot dipped galvanized rigid steel conduit. Where flexibility is required, liquid-tight flexible metal conduit may be used in lengths not to exceed 500 mm. Alternatively, metal clad cable or armored cable per IEC-60502-1 may be used without conduit.

6) All wiring and cables shall comply with the requirements of the National Electrical Code, NFPA 70. Acceptable wire types are SIS, THHN or XHHW; XHHW insulation shall be XLPE. Alternatively, wires per IEC-60227-1, 2, & 3, fire retardant per IEC-60332-1, or cables per IEC-60502-1, fire retardant per IEC-60332-3, may be used (minimum temperature rating 85°C).

7) All wiring shall be a minimum of 2.5 mm² (14 AWG) 600 V stranded copper.

8) Each wire shall be identified with a thermoplastic, slip-on wire marker with permanently printed characters. Snap-on or adhesive type markers are prohibited.

9) Insulated, ring or locking tongue, compression (crimped) terminals shall be provided for all control wiring. A maximum of two conductors may be terminated on a single terminal.

8.11 Grounding

8.11.1 Internal and external grounding terminals shall be provided for grounding cable, armor, shield, and stress-relieving devices.

8.11.2 Transformer core shall be grounded to the frame in accordance with ANSI/IEEE C57.12.01. When enclosure is supplied, the transformer core shall be visibly grounded to the enclosure by means of a flexible grounding conductor.

8.11.3 Transformers shall have provision for a minimum of two equipment grounding connections.


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9 Inspection and Testing

9.1 General

9.1.1 Tests shall be carried out in accordance with the requirements of ANSI/IEEE C57.12.01 and ANSI/IEEE C57.12.91. However, for clarification as to exactly what tests are expected to be performed on the transformers, the Routine Tests and Design Tests required are listed below.

9.1.2 Saudi Aramco Inspection Requirements Form 175-140500 provides information on inspection procedures.

9.2 Routine Tests

Routine production tests shall be performed on the transformers as required by the ANSI/IEEE C57.12.01. They include, but are not limited to:

a) Resistance measurement of all windings b) Ratio c) Polarity and Phase Relation d) No-Load Losses and Excitation Current e) Impedance Voltage and Load Losses f) Dielectric Tests -Applied voltage g) Dielectric Tests -Induced voltage h) Partial discharge (for transformers above 1.2 kV) i) Mechanical -Leak test (for sealed transformers)

Commentary Note:

Transformer manufacturer will supply the magnitude of voltage and current used in each of the specified test.

8.3 Design (Type) Tests

Design tests shall be performed as required by ANSI/IEEE C57.12.01 on one transformer of the type and design offered. They include but are not limited to:

a) Temperature Rise b) Dielectric Tests-Impulse c) Partial Discharge d) Audible Sound Level e) Mechanical -Pressure test (for sealed transformers)


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Commentary Note:

The audio sound level and radio influence level shall not exceed the limits specified in the NEMA Standard Publication No. TR 1 (NEMA TR 1). The nameplate and test reports shall show the measured sound level in decibels.

Revision Summary 29 June 2005 Revised the "Next Planned Update". Reaffirmed the contents of the document, and reissued

with minor changes.


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Data Schedule

Page 1 of 2

Attachment to 14-SAMSS-533 Three-Phase Dry-Type Power Transformers

Description Buyer's Required Values Vendor's Proposed Values

Transformer Voltage:

High Side (Delta) kV ( ) ( ) Low Side (WYE) kV ( ) ( )

Transformer Rating:

(Nominal) kVA ( ) ( )

Type of Transformer:

Indoor ( ) ( ) Outdoor ( ) ( )

Indoor Transformer Cooling Method:

Ventilated Self-Cooled Class AA ( ) ( ) Ventilated Self-Cooled/Forced Air Cooled Class AA/FA ( ) ( )

Impedance: Required

Minimum 4% ( ) ( ) Other (specify in %) ( ) ( )

Enclosure for Indoor Transformer:

Standard (Type 2) ( ) ( ) Other (specify) ( ) ( )

Enclosure Paint Color: Standard (Light gray) ( ) ( ) Other (specify) ( ) ( )

Coil Assembly Construction:

Resin Encapsulated ( ) ( ) Solid Cast ( ) ( )


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Data Schedule

Page 2 of 2

Attachment to 14-SAMSS-533 Three-Phase Dry-Type Power Transformers

Description Buyer's Required Values Vendor's Proposed Values

Tap Changer Range (De-energized):

Standard (2-½% FCAN, 2-½% FCBN) ( ) ( ) Other (specify) ( ) ( )

Auxiliary Power Supply:

120 V AC (single phase) ( ) ( ) Other (specify) ( ) ( )

High Voltage Winding Terminations:

Internal ( ) ( ) Flanged Throat ( ) ( ) Terminal Enclosure ( ) ( ) Incoming Cable Size (mm²/AWG) ( ) ( )

Low Voltage Winding Terminations:

Internal ( ) ( ) Flanged Throat ( ) ( ) Terminal Enclosure ( ) ( ) Outgoing Cable Size ( ) ( ) Neutral Cable Size (mm²/AWG) ( ) ( )

Remarks: BUYER VENDOR

_________________________________________ _____________________________________________

_________________________________________ _____________________________________________

_________________________________________ _____________________________________________

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